Duration, Start and End Issues 2

[wmichael]

Howdy;

I am using MS Project 2003 SP2 and am having issues on the follows;

When entering in a task that has a start date of 8/4/2006, an end date of 8/11/2006. I expect 11 hours to be spent on this task between the dates already set. However, when I input the 11 hours, the start date changes to be 8/10/2006.

I wish to assign one resource to a number of different tasks over a set start and end time, and maintain the duration with the number I initiall input.

Is this clear? May anyone suggest something?

Thanks much!!

~wmichael

"small change can often be found under seat cushions

 

[PDQBach]

In your second para, what you described is not what you did: you didn't mention that you assigned a resource to the task -- and that makes a significant difference.

Also, what you did was what you shouldn't have done. You shouldn't be entering start or finish dates; you should let Project calculate those.

Here's what you need to know:

First:

When you enter a Start date, Project automatically imposes a "Start no earlier than" constraint on the task.

When you enter a Finish date, Project automatically imposes a "Finish no earlier than" constraint on the task.

A task can have only one constraint so entering the Start and then the Finish date left the task with a FNET constraint.

So ... generally speaking: never enter a start or a finish date; by linking tasks you can let project handle the predecessor/successor start/finish dates.

Second:

Project uses the formula W = U * D (Work = resourceUnits * Duration). You can also write that as (you remember this from grade 8): D = W/U or U = W/D

We'll stick to a simple case: just 1 resource assigned to a task.

You entered the start date
You entered the finish date
You assigned one resource.
You changed the work to 11 hours.

Project used the formula D = W (11 hours) / U (1) and changed the duration to reflect the equation. Since the last imposed constraint was "FNET", it had to change the start date. It did.

If you had gone about this in the reverse: enter finish date, enter start date, assign resource, change work then Project would have applied a FNET constraint (when you entered the Finish date), overridden that with a SNET constraint when you entered the Start date) and changed the finish date to Aug 7 when you changed the work.

By now, you've already guess what you have to do: you have to tell Project which of those three (W, D, U) you want to hold constant when you are changing one of the other two. But how?

Display the column: Type. This has three values: Fixed Duration, Fixed Work, Fixed Units.

If you want to hold the Duration constant then set the Type to Fixed Duration and then you can change the Work (to 11 hours). This will keep the Duration constant, will let you change the Work and then Project will calculate the Units (in your example, the Units will be about 23%).

What if you want to change Duration? Then set the task to either Fixed Work (or Fixed Units). Change the Duration and the Units (or Work) will be changed to reflect the change and keep the W = U * D equation equal.

Yes ... you can set the Type to Fixed Work (or Fixed Units or Fixed Durtion) and change Work (or Units or Duration) -- but you shouldn't.

 

[wmichael]

PDQ,

Thank you very much for a most helpful and thorough answer!



~wmichael

"small change can often be found under seat cushions